The background is hereinafter introduced with the discussion of techniques relating to its context. However, even when this discussion refers to documents, acts, artifacts and the like, it does not suggest or represent that the discussed techniques are part of the prior art or are common general knowledge in the field relevant to aspects of the present disclosure.
Aspects of the present disclosure relate to the field of electronics. More specifically, aspects of the disclosure relate to circuitized substrates.
Circuitized substrates (i.e., insulating substrates supporting electric circuits) are commonly used in electronic devices to mount electronic components thereof (so as to protect them from mechanical stresses and to connect them electrically). A typical example is a chip carrier that mounts a (monolithic) chip implementing an Integrated Circuit (IC). For example, the corresponding electronic device may be of the flip-chip type, also known as Controlled Collapse Chip Connection (C4); in this case, the chip is flipped and its terminals are directly connected to facing lands of the carrier, which are generally connected to contacts (for example, balls) of the electronic device arranged on an opposite surface of the carrier by through via-holes, or simply through vias.
Operation of the integrated circuit of the chip often requires one or more auxiliary components. For example, decoupling capacitors (de-caps) are associated with supply terminals of the chip (used to provide a power supply thereto) to reduce undesired noise in the power supply. For this purpose, the (decoupling) capacitors are arranged between the supply terminals receiving a ground voltage and the supply terminals receiving a supply voltage. In this way, the capacitors may shunt (AC) signals superimposed on the (DC) power supply and fluctuations in the power supply caused by switching occurring in the integrated circuit; moreover, the capacitors may store energy to compensate short drops of the power supply due to changing current demand of the integrated circuit.
The capacitors may be integrated on the chip itself. However, special technologies are required to insulate the capacitors from the rest of the integrated circuit (for example, in deep trench structures); these special technologies increase the cost of the chip (and then of the whole electronic device) and they may not be always available. Moreover, the capacitors that may be integrated on the chip are small and then with low capacitance. In any case, this has a significant impact on the manufacturing of the chip; indeed, the integration of the capacitors on the chip requires a dedicated development thereof, with corresponding design, test and deployment.
Alternatively, the capacitors may be mounted on the carrier. However, the limited room available to mount the capacitors only allows the use of relatively small capacitors and then again with low capacitance. Moreover, the connections of the capacitors to the chip may create a bottleneck for the required current density. In any case, the relatively high distance between the chip and the capacitors degrades performance; indeed, the corresponding connections introduce a significantly high line inductance and series resistance.
In both cases, the (relatively) low capacitance that is provided may cause unacceptable variations of the power supply.
Moreover, a complete re-qualification is required for each type of chip and/or for new generations thereof.
An interposer may also be provided between the carrier and the chip to mount the capacitors. However, this significantly increases the size of the electronic device. In any case, the interposer has a detrimental effect on the cost of the electronic device.